Behavioural and cognitive processes play important roles in mediating an individual's interactions with its environment. Yet, while there is a vast literature on repeatable individual differences in behaviour, relatively little is known about the repeatability of cognitive performance. To further our understanding of the evolution of cognition, we gathered 44 studies on individual performance of 25 species across six animal classes and used meta-analysis to assess whether cognitive performance is repeatable. We compared repeatability () in performance (1) on the same task presented at different times (temporal repeatability), and (2) on different tasks that measured the same putative cognitive ability (contextual repeatability). We also addressed whether estimates were influenced by seven extrinsic factors (moderators): type of cognitive performance measurement, type of cognitive task, delay between tests, origin of the subjects, experimental context, taxonomic class and publication status. We found support for both temporal and contextual repeatability of cognitive performance, with mean estimates ranging between 0.15 and 0.28. Repeatability estimates were mostly influenced by the type of cognitive performance measures and publication status. Our findings highlight the widespread occurrence of consistent inter-individual variation in cognition across a range of taxa which, like behaviour, may be associated with fitness outcomes.This article is part of the theme issue 'Causes and consequences of individual differences in cognitive abilities'.

While deficits in metacognition, or the ability to notice and reflect upon mental states has been observed in schizophrenia and linked with poorer concurrent and future function, it is unknown whether these deficits are unique to schizophrenia. Accordingly, this study assessed metacognition using the Metacognitive Assessment Scale-Abbreviated (MAS-A) and the Metacognitions Questionnaire- 30 (MCQ-30) among 26 adults with schizophrenia, 23 with bipolar disorder and 23 healthy controls. Symptom levels of the psychiatric groups were assessed with the Brief Psychiatric Rating Scale. ANCOVA controlling for age and education revealed that the schizophrenia group had lower scores on the MAS-A total and its subscales compared to the bipolar group and healthy controls. The bipolar disorder group also had lower MAS-A scores than the healthy control group. No group differences were found for the MCQ-30. Examination of symptom correlates revealed MAS-A scores were most commonly related to negative symptoms in both clinical groups. The total score and need for control subscale of MCQ-30 was related to total symptomatology and positive symptoms in patients with bipolar disorder. Correlations between the two measures of metacognition revealed that higher MAS-A scores were significantly related to lower scores on the Need to Control Thoughts MCQ-30 subscale.

By the age of six children with DS experience significantly impaired pragmatic communication, with a clear profile of relative strengths and weaknesses. The study highlights the need to teach children with DS pragmatic skills as a component of communication, alongside language content and form.

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